MINDACT is a prospective, randomized, phase III, controlled clinical trial that investigates the clinical utility of MammaPrint, when compared to (or used in conjunction with) standard clinical pathological criteria, for the selection of patients unlikely to benefit from adjuvant chemotherapy. From 2007 to 2011, 6,693 women who had undergone surgery for early-stage breast cancer enrolled in the trial, across 112 centers in nine countries. Participants were categorized as low or high risk for tumor recurrence in two ways: first, through analysis of tumor tissue using MammaPrint; and second, using Adjuvant! Online, a tool that calculates risk of breast cancer recurrence based on common clinical pathological factors (CPFs).
Patients characterized in both clinical and genomic assessments as “low- risk” are spared chemotherapy, while patients characterized as “high- risk” are advised chemotherapy.
Those with discordant results were randomized to use either clinical or genomic risk (MammaPrint) evaluation to decide on chemotherapy treatment. The trial schema below represents the four arms of the MINDACT trial.
The primary objective of the MINDACT trial focuses on the overtreatment of breast cancer patients, and how MammaPrint can be used to help reduce unnecessary prescription of chemotherapy. The primary test group is where clinical pathological factors categorized a patient as high risk, while MammaPrint categorized the same patient as Low Risk (cHigh / MP Low). Patients randomized to use the clinical risk (high risk) received adjuvant chemotherapy in addition to endocrine therapy, while patients allocated to use MammaPrint (Low Risk) received endocrine therapy alone. The results from the primary test showed MammaPrint Low Risk patients had a 94.7% 5-year Distant Metastasis Free Survival (DMFS) without chemotherapy, even in presence of high risk clinical factors.
These results indicate that MammaPrint can help reduce overtreatment of breast cancer patients by 46%, even in the presence of high risk clinical features. The patients in the primary analysis had the following characteristics
MINDACT demonstrates that MammaPrint is the only breast cancer genomic assay that selectively identifies early-stage breast cancer patients with high risk features (lymph node positivity (LN+ 1-3), grade II or III, tumor size >2cm) as Low Risk with no clinically meaningful benefit of chemotherapy. As the only breast cancer recurrence assay developed independent of clinicopathological features, it is the only assay that provides added value to the treatment decision, and can be used in conjunction with clinical factors.